Protective device for electric circuits.



T. E. MURRAY 6; A. V. A. MCHARG'.

PROTECTIVE DEVICE FOR ELECTRIC CIRCUITS.

APPLICATION FILED DECE 2G, 19l3.

Patented July 21, 1914.

onrrnn sraans radian-r FFTCE.

THOMAS E. MURRAY AND ARTHUR V. A. MCHARG, OF NEW YORK, N. Yd; SAIDMCHAEG ASSIGNOR TO SAID MURRAY.

PROTECTIVE DEVICE FDR ELECTRIC CIRCUITS.

Specification of Lettcrs Patent.

I Patented July 21, 1914.

Application filed December 26, 1913. Serial No. 803,775.

- a specification.

' thur V. A. hlcliarg for Letters Patent,

The invention is a protective device for electric circuits, embodying'thc principle set forth in the pending application of Artieria-l No. 803,521, tiled November 98, 1913. A pivoted switch member is held in circuit closing position against the resiliency of a retracting spring, by means of a stop of material destructible by heat which in the present embodiment of our invention is supported upon a pivoted lever. Upon the occurrence of an ovcrloa d current, said member becomes heated sufficiently to fuse or destroy the said stop, whereupon the switch I member is released and being retractedby the spring opens the circuit.

There are certain conditions in the commercial sale of current where the consumer enters into a contract which limits him to current of certain strength at a particular period of time. In such event it is desirable to control his use of the protective device aforesaid, so that after an overload has re leased the switch by destroying the stop aforesaid, he cannot manually reclosc thatswitch and then by fastening it in position avail himself of stronger current which at a different period may be present on the circuit.

In the accompanying drawingsFigure 1 is a vertical longitudinal section of our de vice on the line m, :13 of Fig. 2. Fig. 2 is a transverse section on the line 7 'g of Fig. 1.

Similar numbers of reference indicate like parts.

l is a' base, preferably of porcelain or other insulating material.

2 is a movable switch member having an arm 3, to which is attached a helical retract ing spring 4. As here shown, said switch member is a lever made of two metal parts 5, 6, with an intervening block 7 of insulating material secured to both. One of these parts (6) is pivoted in fixed clips 8. The other part cooperates with fixed contact clips 9. The parts 5, 6 are connected on the upper side or" the lever 2 by a wire 10, which is separated by an air space from the insulating block 7. Circuit terminals 11, 12 are respcctiv-ly connected to clips 9 and 8, so that when the lever 2 is in circuit closing position, the wire 10 is traversed by the current, and is heated thereby. Said wir is to be of such resistance or otherwise to be so, constructed as to become heated When the circuit is overloaded.

13 is a lever pivoted on top of the metal case 14. Said case completely covers the base 1 and parts thereon. and may be locked in placeby any suitable means, as for example a bar :24- hcaded at one end inserted through the base and both walls of the case. and having an opening in its opposite pro jecting end to receive a seal tastening 23. Said lever supports a destructible filament, as hereinafter explained and near its free end is bifurcated, said bi-furcat-ions being downwardly extending curved arms 15, 16 which enter the case 14 through an opening in the upper wall thereof. Carried by said arms is a reel 17, upon which is wound a filament l8 of material fusible 0r destructible by said switch member wh n heated as aforesaid. Said filament extends downwardly on the inner side of arm 16, passes through an opening in. said arm and ex-- tends along the outside thereof, then passes through openings in both arms thus bridging the recess or space between them and is finally secured on arnt 15, Fig. 2. The bridge portion 19 lies upon and in contact with the wire 10 on lever 2. In order to prevent lever 13 from being lifted by spring 4, we provide a spring latch 20 pivoted on case 14 which engages a stud 521 on the side of lever 13.

The operation is as follows: The parts remain in the position shown in the drawinns until an overload. current comes on the circuit. This causes heating of wire 10 and consequent fusion or destruction of filament 1S. Lever 2 is caused by spring at to then rise between the arms 1:"). 1(3 of lever 13 and until it strikes the stop 22 of insulating material on the lower side ')f the top wall of case 'l-ft. as shown in dotted lines. Fig. 1, thus brca ingthe circuit. As the filament 18 has been destroyed, it is obviously im possible to return lover 2 to its normal circuit closing position bv operating lever 13 until filament 18 has been restored. This may be done by raising the arms 15, 16 out of the case, latch 20 being first released, i1n- Winding new filament from reel 17, passing the end of said filament, as before, through the openings in both arms and resecuring it. The new filament 18 then engages wire 10, and by pushing down lever 13, 'leverEZ may now be returned to normal position and secured, as before, by means of latch 20.

We claim:

e 1. A movable switch member adapted to be heated by an overload current in the circuit includingsaid member, means destructible by said heat-ed member for retaining said 15 member in circuit closing position, and

said member in circuit closing position, and means for supporting said retaining means and moving the same into and out of cooperation with said switch member.

2. A movable switch member adapted to be heated by an overload current in the circuit including said member, means destructible by said heated member for retaining said member in circuit closing position, an in- 2 closing case for said parts, and means entering sald case through an opening 1n a wall thereof for supporting said retaining means and movmg the same into and out of cooperation with said switch member.

3. -A movable switch member adapted to be heated by an overload current in the circuit including said member, a movable support having a recess, and a filament destructible ,by said heated member bearing thereon and bridging said recess.

4:. A movable switch member adapted to be heated by an overload current 111 the circuit. mcludmg said member, a movable support having a recess, a rotatable reel on said 40 support, and a filament destructible by said heated member -bearing thereon, wound on said reel and bridging said recess.

5. A pivoted switch member adapted to be heated by an overload current in the circuit including said member, resilient means for retracting said member, a pivoted lever disposed above said switch member, parallel arms depending from said lever and receiving said switch member between them, a

body of material dcstructible by said heated member extending between said arms and across said member, and means for preventing the retraction of said switch member by said resilient means when said dcstructible body is in contact with said member and cuit including said member, resilient means for retracting said member, a case inclosing said parts, a support having a recess at one end and slidable in an opening in a wall of said case, and a filament destructiblc by said heated member on said support, bridging said recess and bearing upon said member.

7. A movable switch member adapted to be heated by an overload current in the circuit including said member, resilient means for retracting said member, a case inclosing said parts, a lever pivoted on said case having a. bifurcated end entering said case through an opening in a wall thereof, and a filament destructible by said heated member extending between the bifurcations of said lever and bearing upon said member.

8. A movable switch member adapted to be heated by an overload current in the circuit conductor including said member, resilient means for retracting said member, a support, and a body of material destructible by heat on said support and engaging said conductor: the said support being movable to carry said body into contact with said conductor when said switch member is in circuit closing position. a

9. A movable switch member adapted to be heated by an overload current in the circuit conductor including said member, re-- silient means for retracting said member, a support, and a body of material destructible by heat on said support and engaging said cimductorz the said support being movable to carry said body into contact with said conductor and thereby to move said switch member into and to retain the same in circuit closing position. i

10. A movable switch member adaptedto be heated by an overload current in the circult conductor including said member, re-.

silient means for retracting said member, a case inclosing the aforesaid parts, a support on said case and entering the same through an opening in a wall thereof, and a body of material destructible by heat on said support and engaging said conductor: the said support being movable in said opening to carry said body into contact with said conductor and thereby to move said switch member into and retain the same in circuit closing position. In testimony whereof we have aflixed our signatures in pre;- ence of two witnesses. THOli IAS E. MURRAY. ARTHUR V. A. MoI'lARG.

Witnesses:

MAY T. MQGARRY, Gnn'rnunn T. Poirrnn. 

